CAIE A-Level Chemistry 5.1.4 Energy Transfer in Chemical Reactions

Practise explaining reaction enthalpy as the balance between energy absorbed in bond breaking and released in bond making.

Exam points

state that breaking covalent bonds requires energy and therefore has a positive energy contribution
state that making covalent bonds releases energy and therefore has a negative energy contribution
classify the reaction from whether energy released by bond making exceeds energy absorbed by bond breaking

[Maximum number: 1]

All the reactants and products of an exothermic reaction are gaseous.
Which statement about this reaction is correct?

The total bond energy of the products is less than the total bond energy of the reactants, and $\Delta H$ for the reaction is negative.

The total bond energy of the products is less than the total bond energy of the reactants, and $\Delta H$ for the reaction is positive.

The total bond energy of the products is more than the total bond energy of the reactants, and $\Delta H$ for the reaction is negative.

The total bond energy of the products is more than the total bond energy of the reactants, and $\Delta H$ for the reaction is positive.

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